Thread-trimming device for sewing machines



Dec.- 8

-4 Sheets-Sheet 1.

'nvnTor. John Kiewic AiTys.

Original Filed June 5, 1922 Dec-. '8, 1925. 1.565.161

1 J... KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Original Filed June 5, 1922 4 Sheets-Sheet 2 Fig.2.

' Q 5| 34 X 47 35 32 I I v SI H' lnvenfgr. 33 John Kmwncg M WM ATTys.

Dec. 8, 1925- 1.565.161

J. KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Original Filed June 5, 1922 4 Sheets-Sheet 5 lnvenTor.

John Kiewicg Dec. 8, 1925- J. KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Original Filed June 5, 1922 4 Sheets-Sheet 4 John K iew is byMMkf Aflys;

Patented Dec. 8, i925 1,565Att 'tif lt'tED STATES PATENT GEFICEQ JOHN KIEVVICZ, 0F BOSTON, MASSACEUSETTS, AISSIGNOR TO THE REECE BUTTON HOLE MACHINE COMPANY, OF BGSTON,

MASSACHUSETTS, A CORPORATION OF MAINE.

TI-IREAD-TREIMIVIING DEVICE FGR SERVING ItIACI-IINES.

Original application filed June 5, 1922, Serial No. 566,010. Divided and this application filed January To all whom it may concern:

Be it known that I, rTOI-IN Kinwioz, a citizen of the United. States, and resident of Boston, county of Suliolk, tdtate of lilassachusctts have invented an Improvement in Thread l rimming Devices for Sewing Machines, of which the following description, .in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

Some sewing machines of that type which are constructed to sew a short seam and then automatically come to rest (a buttonhole sewing machine being an exci'nplification of this type of sewing machine), are provided with thread-trimming means for cutting the needle threadwhich is constructed to seize and hold the needle thread when the seam has been completed, and then to cut the thread between the holding means and the work the thread leading to the needle remaining held in the holding means until after the machine has started to sew the next seam at which time the thread-trimming means is again actuated to cut the held end between the holding means and the work. This type of thread-trimming device trims the needle thread both at the beginning of the seam and at the end of the seam.

The present invention relates to a threadtrimming device of this type and it is herein shown as applied to a buttonhole sewing machine of the type illustrated in United States Patent No. 655,637, August 7th, 1900, or No. 862 238, August- 6th 1907. These buttonhole sewing machines are provided with work-holding means and stitch-forming mechanism arranged to have a relative movement both during the sewing of the buttonhole and subsequently and prior thereto, the relative movement before and after the sewing operation being for the purpose of bringing the parts relatively from buttonhole cutting to stitching position and from stitching position to buttonhole cutting position again.

In the machine herein illustrated the stitch-forming mechanism is mounted on a travelling frame which moves relative to the work-holding means to provide this necessary relative movement, the movement of the frame being derived from the main cam of the machine.

Serial No. 688,926.

One of the objects of my present invention is to provide an improved thread-cutting device for this type of sewing machine in which both the thread cutter and the thread holding means are actuated from the main cam.

Other objects are to improve generally a cutting device of this nature all as will be more fully hereinafter set forth.

In order to give an understanding of the invention I have illustrated in the drawings a selected embodiment thereof which will now be described after which the novel fea tures will be pointed out in the appended claims.

Fig. 1 is a side view of a portion of a buttonhole sewing machine having my improven'ients applied thereto;

Fig. 2 is an under side view of the bed frame showing some of the operative connections for controlling the thread cutter;

Fig. 3 is a plan view of a portion of the bed frame showing my improved threadtrimming meaiis thereon;

Figs. 4- and 5 are fragmentary views showing the thread-trimming means in different positions. 7

The sewing machine shown in the drawings is formed'with a bed plate 1 on which is supportedthe work-holding means comprising the clamp plates 2 on which the work is supported and the pivotally-n'iounted work clamp 3. The stitch-forming mecha;

nism is supported on a head or frame 4.

which travels back and forth on the bed frame I. Said stitclnforming mechanism comprises the upper needle 5 that is su 1iported in a vertically-reciprocating needle bar 6 and an under thread manipulating mechanism not shown) which is carried by a turret 7 that is mounted in suitable bearings in the portion 8 of the head or frame 4, all as illustrated in the above-mentioned patents.

9 indicates the buttonhole cutter by which the buttonhole is cut.

The parts thus far described are such as are commonly found in buttonhole sewing machines of this type and while the operation of the sewing machine will be understood by those skilled in the art it may be stated briefly that when the machine has been brought to rest at the end of the buttonhole the head a is in the full line position Fig. 1 with the needle raised and the work is in buttonhole-cutting position. lVhen the machine is started in operation the head 1 is first shifted to the right to bring the needle into the dotted line position or into stitching position relative to the work and then the stitch-forming mechanism is set in operation and the head 1 continues to move further to the right while the stitching is performed down one side of the buttonhole and is then moved to the left while the stitching is formed on the other side of the buttonhole. When the. buttonhole has been completed the stitclrforming mechanism comes to rest with the needle 5 raised and the head a; is given a further movement to the left into the full line position Fig. 1 thereby bringing the parts relatively into buttonhole cutting position. The buttonhole cutter 9 is actuated while the parts are in buttonhole-cntting position and either before or after the stitching is performed. This movement of the frame 1 in the operation of the buttonhole cutter is derived from a main cam 10 which is carried in a cam housing 11 all as described in the above-mentioned patents.

The thread-holding and cutting means forming the subject of the present invention is mounted on the work-holding means and it includes a thread-holding devic to grip the needle thread at the end of the sewing operation and a cutter to cut the thread both at the end of the sewing operation and at the beginning of the next sewing operation. The thread holder or thread gripper is in the form of an arm 12 pivoted at 13 to one of the pivotally-mounted arms 14 that carry the work clamps 3. This arm 12 is formed at its end with a hooked portion 16. Co-operating with the thread-gripping arm is a gripping plate 17 which is secured to the arm 141- as shown at 18, said plate 17 being situated directly beneath the hook 16 and in engagement therewith. The thread-gripping arm 12 is acted on by a spring 19 which tends to hold it in the position shown in Fig. 3, in which position it is located at one side of the line of stitching. Just before the stitching on the buttonhole is completed the arm 12 is swung over into the position shown in 1 thus carrying the hook 16 to the opposite side. of the line of stitching and when the but-tonhole (indicated by the dotted line 20) is completed and the stitch-forming mechanism has come to rest with the needle raised, the portion of the needle thread 21 extending from the needle 5 to the work will be behind the hook 113. The arm 12 is then given a movement into the position shown in Fig. 5 during which time it engages the needle thread 21 between the work and the needle and clamps the thread between the book 16 and the plate 17.

The thread cutter is shown as a cutting blade 22 operating beneath the plate 17 and carried by a swinging arm which is pivoted at 241 to an extension 25 extending from one of the arms 1%. This thread cutter is acted on by a spring 26 which normally holds it in retracted position shown in Figs. 3 and 1, and means are provided which operate to give the thread cutter a forward cutting movement into the position shown in Fig. 5, both at the end of the stitching operation and at the beginning of the next stitching operation. The movement of the thread cutter at the end of the stitching operation occurs after the thread has been gripped by the thread gripper 12 and results in severing the thread lfictween the thread-holding means and the worlt. The end of the thread leading from the needle remains gripped in the thread-holding means until after the stitching has been started on the next seam, at which time the thread cutter operates again to cut the held end between the holding means and the work. Both the cutter and the thread gripper are actuated from means associated with the main cam 10.

Extending vertically through the bed plate 1 is a rock shaft 27 having at its upper end an arm 28 that is adapted to engage the arm 12 of the tln-ead-gripping means and swing the latter into the position shown in Fig. 1. This rock shaft 27 has an arm 29 fast thereto beneath the bed plate which is formed with an tip-standing lug 30 that cooperates with a shoe portion 31 formed on a lever 82 that is pivoted at 33 to the cam housing 11. This lever 32 has a projection or finger which co-operates with a cam member that is rigid with the main cam 10, said cam member 35 being formed on a hub portion of the main cam 10. The cam member is concentric throughout the greater portion of its periphery and is provided with the rise 36. The cam 10 and coin sequently the cam member makes one rotation for each sewing operation and the rise 36 is so positioned that it will engage the finger 841 and actuate the lever 32 just before the stitching on the huttonhole is completed.

The lever 52 is held with the finger 34c engaging the periphery of the cam 35 by means of a spring 37 and the arm 28 is normally held out of engagement with the thread-holding arm 12 by means of a spring 38. Therefore so long as the linger 34 engaging the concentric portion of the cam member 35 the thread-gripping member 16 will be retained in the position shown in Figs. 3 and 5. 7

Just before the sewing on the buttonhole is completed the rise 36 passes under the finger Set thus swinging the lever to the right in Fig. 2 and bringing the shoe portion 31 against the lug thereby turning the rock shaft 27 and swinging the finger 23 into the position shown in Fig. 4 with the result that the hook 16 of the thread gripper is carried across the line of stitching.

This occurs before the stitching on the but' tonhole has progressed to a point where this movement of the hook will be interfered with by the reciprocations of the needle. The rise 36 is of sufficient extent to hold the thread-gripping hook 16 in the position shown in Fig. 4 until after the stitching on the buttonhole has been completed and the stitch-forming mechanism is brought to rest, at which time the needle 5 will be raised and the needle thread 21 extending from the work to the needle will lie behind the hook 16 as shown in Fig. 4. At this time the rise 36 passes out from under the finger 34 thus allowing the springs 37, 38 and 19 to restore the parts to the position shown in Figs. 3 and 5. During the movement of the hook 16 from the position shown in Fig. 4 to that shown in Fig. 5 it engages the needle thread 21 and draws the latter over the edge of the plate 17 and clamps the thread between itself and said plate as above described.

F or operating the thread cutter I have provided a sleeve or hollow shaft 39 which extends through the bed plate 1 and through which the rock shaft 27 extends. This hollow shaft 39 has rigid therewith at its upper end an arm 40 by which the thread cutter is actuated, said arm being acted on by a spring 41 which normally holds it in retracted position. Fast to the hollow shaft 39 below the bed plate 1 is another arm 42 having a lug or finger 43 adapted to be engaged by the shoe portion 44 of a lever 45 which is also pivoted to the cam housing 11 at 33. This lever 45 has a portion 46 which co-operates with a cam member 47 also rigid with the main cam 10, said lever 45 being held against the periphery of the cam 47 by a spring 48. j

The cam 47 is formed with two notches 49, 50 arranged so that as it rotates the projection 46 on the lever will drop into each notch and will then be carried out of the notcln henever one of the notches is presented to the projection 46 the spring 48 will give the lever 45 a quick movement to the left Fig. 2, such movement bringing the shoe 44 into engagement with the finger 3 and acting through the arm 42 to turn the rock shaft 39 so as to carry the finger 40 against the thread-cutting arm 23. This gives the arm 23 its thread-cutting movement.

The notches 49 and 50 are each formed with one side 51 extending substantially radially and the other having an inclined relation so that as each notch passes under the project-ion 46 said projection will drop into the notch with a quick movement under the influence of the spring 48 thus giving the lever 45 a quick cutter-actuating movement. The cutting movement of the thread cutter 22, therefore, results from the action of the spring 48.

The two notches 49 and 50 are so situated that one notch will come under the projection 46 at the end of the buttonhole just after the thread gripper has gripped the needle thread and the other notch will come under the projection 46 just after the stitching on the next buttonhole has been started. Therefore, with this construction the needle thread will be seized and held at the end of the buttonhole, the thread cutter will sever the thread between the holding means and the work and the thread will continue to be held until after the first few stitches 011 the next buttonhole have been completed, at which time the cutter is actuated a second time to cut the held end of the thread, thus trimming the thread at both ends of the buttonhole The cam housing 11 is secured to and moves with the head 4 so that the levers 32 and 45 have a movement back and forth relative to the shafts 27, 39. The shoe portions 31 and 44 are thus provided on the levers so that they will not lose engagement with the projections 30 and 43 during the travelling movement of the head 4.

This application is a division of m copending application Serial No. 566,010, filed June 5th, 1922.

I claim.

1. In a sewing machine, the combination with a bed plate, of work-holding means carried thereby, stitch-forming mechanism, a thread-holding device mounted on the work-holding means, a rock shaft extending vertically through the bed plate and journalled therein, said rock shaft having fast thereto one arm above the bed plate for actuating the thread-holding means and another arm below the bed plate, a cam-actuated lever to engage the second arm thereby to oscillate the rock shaft, and means to cut the thread.

2. In a sewing machine, the combination with a bed plate, of work-holding means carried thereby, stitch-forming mechanism, a cam for giving the stitch-forming mechanism and work-holding means a relative movement, a thread-holding device, a rock shaft extending vertically through the bed plate and having two arms fast thereon, one above the bed plate for actuating the thread-holding device and the other below the bed plate, and means associated with said cam for actuating the rock shaft.

3. In a sewing machine, the combination with a bed plate, of work-holding means carried thereby, stitch-forming mechanism, a cam for producing relative movement between the work-holding means and stitchforming mechanism, a thread-holding device and a thread-cutting device mounted on the work-holding means, two rock shafts extending vertically through the bed plate, each having fast thereto an arm above the bed plate and another arm beneath the bed plate, the arms above the bed plate adapted to actuate the thread cutter and gripper, and levers beneath the bed plate co-operating with the other arms of the rock shafts to actuate the latter, and means associated with the main cam for controlling said levers.

4. In a sewing machine, the combination with a bed plate, of work-holding means carried thereby, stitch-forming mechanism, a cam for giving the stitch-forming mechanism and work-holding means a relative movement, a thread-h0lding device, a rock shaft extending vertically through the bed plate and having two arms fast thereon, one above the bed plate for actuating the threadholding device and the other below the bed plate, means associated with said cam for actuating the rock shaft, and means to cut the thread.

In testimony whereof, I have signed my name to this specification.

JOHN KIEWiCZ. 

